An estimated 2.3-3.5 million Americans are homeless during a given year. Cigarette smoking is over three times more common among homeless individuals in comparison to the US general population, contributing to excess morbidity and mortality. Despite this disparity, there is relatively little research on the tobacco use characteristics and predictors of readiness to quit in homeless smokers. Few studies have rigorously tested smoking cessation interventions in this population, and those conducted to date have demonstrated generally modest results. Addressing tobacco use in this vulnerable population will require a better understanding of the problem and a novel approach to its treatment. To address these gaps in evidence, the principal investigator (PI) proposes a career development program that blends rigorous methodologic training by Harvard faculty with an innovative research agenda that builds upon a unique academic-community partnership between Massachusetts General Hospital (MGH) and Boston Health Care for the Homeless Program (BHCHP). This career development plan has three scientific objectives: 1) To estimate smoking-attributable mortality, morbidity, and health care utilization in a cohort of homeless adults, 2) To describe the tobacco use characteristics of homeless smokers and assess the factors influencing decisional balance for smoking, reward value of smoking, and readiness to quit, and 3) To conduct a pilot randomized controlled trial to assess the feasibility and efficacy f a cash-based contingency management (CM) tobacco cessation intervention for homeless smokers. CM strategies utilize financial incentives to reinforce smoking reduction and cessation; such methods have shown promising results in promoting smoking cessation in other vulnerable populations but have never been tested in homeless smokers. The proposed research project complements the National Institute on Drug Abuse (NIDA) strategic focus on developing novel behavioral treatments and reducing disparities in drug addiction in special populations. Additionally, this project taps into several other areas of interest at NIDA, including epidemiology, health services, and medical consequences. To complement his content expertise in homeless health care, the PI has outlined a plan for acquiring expertise in tobacco cessation research, behavioral science, intervention design, and research in homeless populations through formal graduate-level coursework as well as mentorship by an exceptionally-qualified team of accomplished senior scientists who are internationally-recognized leaders in areas of research directly relevant to the current proposal. The successful completion of this career development plan will establish the PI as an expert in tobacco use among homeless individuals and enhance his ability to conduct patient-oriented research as an independent investigator focusing on this and other high-risk health behaviors in homeless persons.